2005 data (pdf):
Percentage of employees who were paid minimum wage: 4.3
Percentage of minimum-wage workers who were
- working part-time: 59.2
- between 15 and 19 years old: 44.5
- students living at home: 33.2
- heads of a household with children under 18: 5.4
The Toronto Star, in its recent series on the 'working poor', offers as support for its call to increase the minimum wage the 'Questions by Experts' section of the UN Committee on Economic, Social and Cultural Rights' report on Canada:
On the minimum wage, it appeared that this did not allow for a decent standard of living, as it was below the amount needed to keep people above the poverty line, and this was contrary to the Covenant, and [the Expert] asked what would stop a country as wealthy as Canada from implementing a minimum wage that provided a decent standard of living.
I don't know what sort of expertise the The Expert is supposed to have, but the answer to his question is this: the minimum wage is a remarkably ineffective instrument for dealing with poverty. Labour demand curves slope downward in rich countries, too.
Update: A longer discussion of the effects of the minimum wage on employment and poverty is here.